ACO,Hi there!!
I believe Sam the 25lb kitty is a Maine Coon,25lb's is not unusual for that breed.
I had a male Maine Coon a looong time ago and he was about that weight too.

Sam is a cross between an English Shorthair and a Main Coon. He looks like an English Shorthair but has some features of the Main Coon. Both of which are large breed animals. The male English Shorthair can be 10 kg / 22 lbs.